Rosai Dorfman Disease in Mandible: A Rare Case Report

Rosai Dorfman disease is generally defined as a massive bilateral painless cervical lymphadenopathy accompanied with both fever and leukocytosis with neutrophilia. Additionally, it may possibly be associated with polyclonal hypergammaglobulinemia, reversal of CD4/CD8 ratio, the elevated erythrocyte sedimentation rate (ESR), microcytic anemia, and thrombocytosis. Rosai-Dorfman disease is known as a benign self-limiting disease, so no treatment is required in many cases, although it causes death in some cases by involving vital organs like kidney. The treatment is required when there is a life-threatening situation such as airway obstruction or involvement of vital organs such as kidney, liver, and lower respiratory tract. The required treatment choices include steroid therapy, chemotherapy, radiotherapy, and surgery. Surgical treatment is performed for bulk removal to resolve the obstruction caused by the mass as well as taking biopsy for the definite histopathologic diagnosis of disease. A 26-year-old man was referred to oral and maxillofacial surgery (OMFS) clinic of Taleghani hospital with chief complaints of pain and swelling of left submandibular space. According to the patient himself, the swelling had been started three months earlier. After rejecting dental source of the lesion, we decided to remove the mass by excisional biopsy concerning the patient’s discomfort. Histopathology report verified Rosai Dorfman disease as definite diagnosis of the mass.

RDD is histologically defined as lymphatic sinus dilatation caused by histiocyte proliferation that is very similar to a malignant neoplasm, despite its benign origin.
Correspondingly, it usually shows slightly higher incidence rate in male patients [3,[11][12]. It can occur in all age groups, but it more tends to affect children than adults [13]. Although it seems to be idiopathic, it is a disorder of the mononuclear phagocyte and an immunoregulatory effector (M-PIRE) system [14]. The altered immune responses and infectious agents such as Varicella Zoster, Herpetic viruses, Epstein-Barr, Cytomegalovirus, Brucella, and Klebsiella, are also announced as possible reasons for the incidence of RDD [10].
In about 43% of cases, RDD occurs in extra nodal form without any lymphadenopathy making this disease hard to be differentiated from other similar conditions [3,[15][16][17][18]. Of note, the extra nodal form shows poorer prognosis compared to the nodal form [18]. Soft tissue of head and neck regions and the paranasal sinuses and the nasal cavity are the most common sites that are involved in this disease [16,19]. Some of the case reports  [7,20]. The treatment plans proposed for RDD vary from steroid therapy, antibiotics, radiotherapy, chemotherapy, surgery to the combination of these methods; however, no definite treatment has been introduced for this disease yet [3]. Due to the chronic, relapsing nature of this disease, treatment is only necessary in persistent or worsening cases [21]. Of note, it can be mortal by infiltration into vital organs [22].  (IHC), staining for CD1 and S100 had been performed on the sample that confirmed our diagnosis. We decided not to remove the right lesion due to its smaller size, but a minimum dose of Prednisolone (5 mg that gradually reduced to 2.5 mg) was prescribed and routine follow up scheduled for the patient. The patient's condition was followed up for 2 years and no recurrence of lesion had been observed (Figure 4).  as CD1a and CD68 antigens [10,[23][24]. The most common sign of the disease is painless cervical lym-phadenopathy [25][26], which is represented as a cervical mass. However, in our case, pain was represented in the swelling zone. This may lead to various differential diagnoses such as infectious, lymphomatous, and nonlymphomatous causes, while massive painless bilateral lymph node enlargement of neck, especially in younger patients and adolescents, greatly increased the chance of detecting RDD in the differential diagnosis [27][28][29]. As well, the associated lymphadenopathy of RDD is detectable in magnetic resonance imaging (MRI), medical CT, sonography, and scintigraphy. The sonographic pattern of the involved nodes is similar to malignancies [28]. The increased uptake of gallium and raised metabolism of F-FDG on PET scan are detectable in nuclear imaging [11,[29][30]. Although the mass is visible using paraclinical imaging techniques, histopathological analysis is necessary for the definite diagnosis of RDD [25,28]. RDD is known as a benign self-limiting disease, so no treatment is needed in many cases [31,[33][34], although some cases of death by vital organs like kidney [22], have been reported. The treatment is required when there is a life-threatening situation such as airway obstruction or the involvement of vital organs such as kidney, liver, and lower respiratory tract [3].

Case Presentation
The required treatment choices include steroid therapy, chemotherapy, radiotherapy, and surgery [9]. Surgical treatment is performed for bulk removal to resolve the obstruction caused by the mass as well as taking biopsy for the definite histopathologic diagnosis of disease.
FNA and lymph node removal can also be helpful in better diagnosing RDD [9], as we used in our case before the surgical excision.
An informed consent of the patient was obtained to use the information and photos of the patient in the article.

Conclusion
RDD is a rare, benign, and self-limiting disease. Although few cases of RDD have been reported up to now, the similarity of signs and symptoms of RDD, tuberculosis, and malignant tumors like lymphomas, makes the correct diagnosis of the disease more challenging. Histopathology is the definitive way for diagnosing RDD by detecting emperipolesis. Treatment is not necessary in benign cases, although in life-threatening cases, surgical treatment is needed to avoid mortality. The recur-rence of disease is probable; therefore, routine followup is recommended.

Conflict of Interest
Authors declare that there are no conflicts of interest in this study.